Magda Aparecida de Lima

Metano entérico de bovinos leiteiros em condições tropicais brasileiras

The objective of this work was to quantify methane (CH4) emission using the sulfur hexafluoride (SF6) tracer technique, by dairy cattle on pasture in Brazilian tropical field conditions. Measurements were performed in the rainy season, with Holstein and Holstein x Zebu crossbred, from lactating and dry cows and heifers grazing fertilized Tobiata grass, and heifers grazing unfertilized Brachiaria grass. Methane and SF6 concentrations were determined by gas chromatograph. Methane emissions by lactating cows varied from 13.8 to 16.8 g/hour, by dry cows from 11.6 to 12.3 g/hour, by heifers grazing fertilized grass was 9.5 g/hour and by heifers grazing unfertilized grass varied from 7.6 to 8.3 g/hour or 66 to 72 kg/head/year. Methane emission per digestive dry matter intake (DMDI) varied from 42 to 69 g/kg DMDI for lactating cows, 46 to 56 g/kg for dry cows, 45 to 58 g/kg for heifers grazing fertilized grass and 58 to 62 g/kg for heifers in unfertilized grass pasture. The CH4 emission measured on dairy cattle feeding tropical grasses was higher than that observed for temperate climate conditions.

Efeitos de dietas contendo Leucaena leucocephala e Saccharomyces cerevisiae sobre a fermentação ruminal e a emissão de gás metano em bovinos

This research was to evaluate the effect of Leucaena (Leucaena leucocephala) and yeast (Saccharomyces cerevisiae) in diets for bovines on ruminal metabolism, including pH, volatile fatty acids, and ammonia and methane production. Four crossbred male cattle (800 kg LW) rumen cannulated were distributed to a 4 × 4 Latin Square design, in 2 × 2 factorial arrangement, composed by two levels of Leucaena (20% and 50% DM) and coast-cross grass hay, with or without yeast. No differences were observed in rumen pH (mean 6.82) and ammonia concentrations that varied from 18.71 to 21.28 mg/100 mL of ruminal fluid. There was interaction between Leucaena levels and yeast in the total concentrations of VFA. No differences were observed in the concentrations of acetic acid, but the animals fed 50% of Leucaena with yeast showed higher propionic acid concentration (19.14 mM). Methane emissions were reduced by 12.3% in relation to the same diet without yeast and in 17.2% when the animals were fed 20% of Leucaena with yeast. There was a noticeable associative effect of Leucaena when fed in high level (50% DM) and yeast in the reduction of methane emission and better rumen fermentation with possible reduction of energy loss and better energy efficiency for the animals.

Ruminal methane emission by dairy cattle in Southeast Brazil

Gases gerados durante o processo de fermantacao ruminal, metano em particular, representam nao so uma perda parcial de energia da alimentacao como tambem sao apontados como importantes fatores do efeito-estufa. Quantificaram-se as taxas de emissao de metano (CH4) ruminal por vacas em lactacao, vacas secas e novilhas com idade media de 24 meses, em pastejo sob condicoes tropicais do sudeste brasileiro, utilizando a tecnica do gas tracador hexafluoreto de enxofre (SF6). Foram utilizados quatro animais para cada categoria, distribuidos em quatro blocos. As medicoes foram realizadas em fevereiro e junho de 2002, com animais da raca Holandesa e Mestica Leiteira Holandes ¾ x Gir ¼ - Mesticas, mantidos em pastagem de capim-Tanzânia (Panicum maximum Jacq. cv. Tanzania) e capim-braquiaria (Brachiaria decumbens cv. Basilisk) adubadas, e tambem novilhas de ambas as racas em pastagens de capim-brachiaria sem adubacao, simulando as condicoes de producao extensiva. As concentracoes de CH4 e SF6 foram determinadas por cromatografia gasosa. Foram encontradas diferencas na emissao de metano (p < 0,05) entre os grupos geneticos. Animais da raca holandesa produziram mais metano (299,3 g dia-1) que as mesticas (264,2 g dia-1). Vacas secas e novilhas produzem menos metano (g dia-1) que vacas em lactacao. A media de emissao de metano (g dia-1) pelas vacas secas e novilhas foi de 268,8 e 222,6 g respectivamente e as vacas em lactacao 353,8 g. Os animais da raca holandesa, com maior potencial de producao de leite, perderam menos CH4 (p < 0,05) por unidade de materia seca ingerida (19,1 g kg-1) que as mesticas (22,0 g kg-1). A producao de metano pelas novilhas mantidas em pastagens adubadas (sistema intensivo) foi de 222,6 g dia-1, maior (p < 0,05) que os animais desta categoria em pastagens nao adubadas (179,2 g dia-1). A producao de metano variou em funcao da categoria de animal e pelo sistema de producao imposto aos animais.

Methane emissions and estimates of ruminal fermentation parameters in beef cattle fed different dietary concentrate levels

Using sorghum silage, the effect of roughage/concentrate ratios was evaluated on nutrient intake, digestibility, ruminal parameters and methane production by beef cattle. Three treatments (0, 30 and 60% of concentrate in DM of the diet) were distributed in three Latin squares, with nine animals and three periods. Dry matter intake increased as the grain concentration in diet increased; pH showed opposite behavior. Methane emissions were lower for animals fed the diet exclusively with sorghum silage as compared with those fed 30% of concentrate, but was similar to that of animals receiving 60% of concentrate. Losses of ingested gross energy as methane were reduced by 33% when grain concentration was increased in the diet. Concentrations of propionic and butyric acids were greater in diets with grain concentrate; acetic acid concentration was not affected. Concentrate in diet increases available energy for the metabolism, measured by lower losses of ingested gross energy as ruminal methane.

Influence of different supplements and sugarcane (Saccharum officinarum L.) cultivars on intake, digestible variables and methane production of dairy heifers under tropical conditions

The sulphur hexafluoride (SF6) gas tracer method was used to measure methane (CH4) production of crossbred (3/4 Holstein x Zebu) dairy heifers fed two types of sugarcane (Saccharum officinarum L.; cultivar IAC-862480 (CC1) or cultivar IAC-873184 (CC2)) and supplemented with urea or concentrate. The study was performed at Embrapa Southeast Cattle, São Carlos, SP, Brazil, using a completely randomised design. Differences between treatments were significant for digestibility of dry matter, organic matter and energy. When animals were supplemented with urea differences between sugarcane cultivars did occur for NDF consumption, but not for daily methane production. This suggest that variation in chemical composition of sugarcane did not affect bovine ruminal CH4 emissions. Concentrate inclusion in animal diet increased digestible organic matter intake, improving the nutrient intake by animals, but did not reduce CH4 production expressed as a percentage of gross energy intake.